I always thought that the timing of Captain Jack Harkness and Steve Rogers both serving in WWII and then both being alive in present day, AND both fighting aliens, was too much of a coincidence for them to not have bumped into each other on multiple occasions. Seeing Jack meeting (and hitting on all of) the Avengers would be hilarious.
And yes, he would hit on all of them. Even Hulk. Especially Hulk.
And yes, he would hit on all of them. Even Hulk. Especially Hulk.